The invention relates to an apparatus for forming a partial stack through the separation of printed sheets, which partial stack extends perpendicularly with respect to the printed sheets standing one behind the other, which apparatus is connected downstream of a feeding apparatus conveying the printed sheets in a preferably imbricated formation approximately perpendicularly to the direction of stack forming and which is provided with an approximately horizontal stack guide along which a multi-component separating device is arranged, which is intended for forming the partial stacks and which can be powered, which components of the separating device, are each provided with spreading elements of a spreading apparatus keeping the printed sheets apart in proximity of the stack guide, which spreading elements plunge between two printed sheets which follow one another fold forward, of which spreading elements the spreading element that is leading in the direction of stack forming is associated with the rear end of a formed partial stack and the trailing spreading element is associated with the front end of a subsequent stack of printed sheets or partial stack, and with which spreading elements a support element of a support apparatus is associated which support element can be driven into the stack of printed sheets between the spreading elements keeping the printed sheets apart from one another.
An apparatus of the type described above is disclosed in European patent application EP-A-0 623 542.
A principal demand with respect to an apparatus of this type is the reliable and damage-free separation of the printed sheets between two partial stacks to be formed which are first transported and deposited for intermediate storage or which, immediately afterward, are separated again during further processing.